Semiconductor memory devices are widely used. Representative examples of semiconductor devices include an Electrically Erasable Programmable Read-Only Memory (EEPROM) capable of performing writing, reading and erasing operations by applying different control voltages.
FIG. 1 illustrates a schematic circuit diagram showing components of a semiconductor device control circuit.
As illustrated in FIG. 1, EEPROM 10 has three control voltage terminals CG, RBL and TG for performing operations for programming, reading and erasing data. Control voltage terminals CG, RBL and TG are respectively connected to transistors 20, 30 and 40. Transistors 20, 30 and 40 are N-channel Metal Oxide Semiconductor (NMOS) transistors, which perform the programming, reading and erasing operations of EEPROM 10 by selective transmission of external signals.
The control terminals of transistors 20, 30 and 40 are connected to first external terminal 50 so as to receive an operation voltage. First transistor 20 connected to control voltage terminal TG of EEPROM 10 is connected to second external terminal 60. Second transistor 30 connected to control voltage terminal RBL of EEPROM 10 is connected to third external terminal 70. Third transistor 40 connected to control voltage terminal CG is connected to fourth external terminal 80.
In a EEPROM having such a design, however, due to the process characteristics of a selection transistor, if a gate breakdown voltage is lower than an EEPROM program voltage, it is impossible to program data in the EEPROM.